1. Field of the Invention
The present invention relates to a magnetic tape apparatus and in particular, to a magnetic tape apparatus constituted in such a manner that positioning is performed according to a servo information of a magnetic tape.
2. Description of the Related Art
Conventionally, in a magnetic tape apparatus having a magnetic tape mounted, the positioning of a magnetic head with respect to the magnetic tape has been performed according to a servo information of the magnetic tape, thus increasing the recording density in the track direction.
However, in the aforementioned conventional example, when the position of the magnetic head is shifted (off track) due to an external force such as a shock, this may destroy a data in the adjacent track if data writing is in progress, or may remarkably lower the reliability of a data reproduced if data reading is in progress.
It is therefore an object of the present invention to provide a shock-resistant magnetic tape apparatus which eliminates a danger of data destruction in adjacent tracks which may be caused by an external force such as a shock. More specifically, the present invention provides a magnetic tape apparatus which eliminates data destruction of an adjacent track if data writing is in progress or recovers reliability of a reproduced data if read out is in progress when the shock is applied to the magnetic tape apparatus.
The magnetic tape apparatus according to the present invention comprises: a magnetic tape having a servo region for head positioning; a magnetic head arranged to face a recording side of the magnetic tape; a head holding mechanism for holding the magnetic head and reciprocally move the magnetic head in a width direction of the magnetic tape; and a head positioning mechanism for urging the head holding mechanism with a predetermined moving force.
The apparatus further comprises: a main controller for driving the head positioning mechanism according to a servo information recorded on the magnetic tape and controlling operation of respective components of the apparatus such as the magnetic tape running drive apparatus; and a write control circuit provided adjacent to the main controller, for controlling to write a predetermined information transmitted from an upper node apparatus to the magnetic head.
Furthermore, the apparatus comprises a shock sensor provided in the head holding mechanism for detecting a predetermined possible shock force applied to the head holding mechanism, and converts a detected shock into a predetermined signal; and a stop signal output circuit operating according to an output from the shock sensor, so as to supply a predetermined operation stop signal to the main controller and the write control circuit.
Thus, if the apparatus is subjected to a shock, the shock sensor arranged in the head holding mechanism detects the shock as an external force and the stop signal output circuit produces a predetermined operation stop signal so that the entire apparatus is disabled to write. This effectively prevents deterioration of the magnetic head and increase the durability of the entire apparatus.
The main controller may have a retry operation control function which operates as follows: upon reception of the operation stop signal from the stop signal output circuit, the main controller is immediately activated to control to stop the head positioning mechanism, the tape running drive mechanism, and other components; after a lapse of predetermined time, the main controller is again activated to activate the head positioning mechanism, the tape running drive mechanism, and the write control circuit; and after a predetermined amount of reverse drive, the respective components resume their operations at the same timing before the stop control.
This enables to assure reliability of a reproduced data during a read operation, thus improving the reliability of the entire apparatus.
Moreover, the stop signal output circuit (comparator) may have a shock value comparison function for comparing the output value from the shock sensor to a reference value from a slice level specifying circuit, and if the former is greater than the latter, producing the operation stop signal.
This enables effectively eliminate malfunction which may be caused by a noise or the like. Furthermore, the head holding mechanism may be constituted by: a head holder for holding one side of the magnetic head arranged to face a data recording surface of the magnetic tape; and a guide mechanism for guiding the head holder in a direction of the width of the magnetic tape.
This facilitates assembling and adjustment of the head holder and improves the structural accuracy.
Moreover, the head positioning mechanism may be constituted by a through hole screw formed in the head holder and extending in the direction of the head holder, a male screw engaged with the through hole screw, and a motor for urging the male screw in a normal direction or a reverse direction.
The aforementioned configuration enables to position the magnetic head quickly and accurately. Furthermore, the magnetic head can be stopped at a stable position.
Furthermore, the shock sensor may be provided on the other side (second side opposite to the first side) of the head holder.
This enables to detect a shock almost identical to the shock applied to the magnetic head.
Moreover, a spring mechanism may be provided for always urging the head holder in one direction along the guide mechanism.
This enables to smoothly adjust the position of the magnetic head which moves together with the head holder. This further improves stability of the stop position.